2000 Jeep Cherokee stalls after warm-up

This is the original problem and has not changed. You can view this entire thread at www.jeepforum.com under the same title I used here. It is pretty sick. This site was recommended by one of the guys over there. I have also included the list of things tested and replaced along with the very last post. Thanks for your help.

O.K. here is the deal I have a 2000 Jeep Cherokee Sport 4x4 automatic that stalls after about 30minutes +/-. This goes back to earlier this year when it became hard to start. Come to findout it was the crankshaft sensor. Replaced and all was good. Then it started to act up again. 3months later. This time I had to have it towed, but I was near a parts shop so I borrowed their OBDII tester and it came up with crank or camshaft sensor. So, I bought the camshaft sensor this time replaced in the field. It started and died after giong around the parking lot one time. Called tow truck. At the shop they said the crank sensor went. They replaced it, I drove it one day and it died again. Back to the shop. This time they said the computer was dead. Jeep ended up back at my house after I got pi**ed-off at the shop for ordering the incorrect computer and letting two weeks go by without keeping me clued in on what happened. So, I have a car that dies after it warms up. It gets to just about 210 degrees and will shut-down. I have replaced all the above parts, switched the ASD relay with the cooling fan relay to no avail. I have checked all the connections and vaccuum lines. Nothing seems to be out of wack. It is now sitting on the others side of my neighborhood, after I test drove it today because it ran for more than 30minutes today. My mistake!!! Help me out. I want this car fixed, but I'm not sure where to go from here. Help me out. I'm not afraid to get my hands dirty, but I'm at a loss as to what to do next.
1. Crank Position Sensor replaced twice. The CPS has tested good
2. Cam Position Sensor replaced. Put the old one back with no change in problem
3. ECM(PCM) Replaced problem still happens Old or New
4. Removed and cleaned Throttle Body
5. Tested and replaced the TPS O.K.
6. Tested all 4 of the O2 sensors O.K.
7. Tested Coolant sensor O.K.
8. Tested MAT Sensor O.K.
9. Tested the Coil Rail at room temp O.K. Replaced with new
10. Tested and swapped the ASD Relay O.K. Replaced with new
11. Tested and Swapped Fuel Pump Relay O.K.
12. Cleaned went through every connection both electrical and vacuum found nothing obviously wrong
13. Tested fuel pressure replace fuel pump on recommendation of dealership
14. Replaced spark plugs

This is the continuing nightmare. I'm running out of ideas and the fustration now has me just about to the breaking point.

I replaced the ignition coil. Started and ran fine but died just as before. It only kicked up the 1391 code once since the coil replacement. It stalls while just sitting in the driveway with no codes or CEL. This is just too strange! I started it up and let it run while I disconnected sensors one at a time. Each sensor turned on the CEL and came up with a corresponding code that matched what I had just unplugged. The only exception to this rule was the IAC Motor; no code came up when it was disconnected. I know that the idle goes up and down as the A/C compressor comes on and off and I believe that the IAC Motor controls that idle function. So, with the IAC unhooked and the A/C on, the idle did not fluctuate when the compressor cycled. I plugged the IAC back in and the idle rose and fell with the A/C cycle. I guess that is normal. I also, took the time to remove the IAC Motor and give it another cleaning. The only other thing that may indicate that something is wrong was that when I unplugged the MAP Sensor the engine idle speed rose and fell and then stalled out in addition to turning on the CEL and sending up a code. Is that normal? Is there anything else that could cause this car to stall like this? It is slowly kicking my A**! I’m about to put a For Sale As Is on it and cut my loses.

The AC adds alot of drag on the motor so it has to up the idle to compensate. It sounds like you replaced damn near everything...... If you have not done anything with your IAC except unplug it then you need to remove it, clean it and reinstall. That should fix the problem concidering you replaced everything else. Your throttlebody also has an adjustment hex screw for the throttle blade that may help. It should not be the problem but adjusting it so that your throttle blade is cracked open should keep you running. Oh, unplugging your MAP sensor will throw a code as that sensor tells the ECM how much air is entering the engine. Hope this helps!!

ColoradoRaptor said:

The AC adds alot of drag on the motor so it has to up the idle to compensate. It sounds like you replaced damn near everything...... If you have not done anything with your IAC except unplug it then you need to remove it, clean it and reinstall. That should fix the problem concidering you replaced everything else. Your throttlebody also has an adjustment hex screw for the throttle blade that may help. It should not be the problem but adjusting it so that your throttle blade is cracked open should keep you running. Oh, unplugging your MAP sensor will throw a code as that sensor tells the ECM how much air is entering the engine. Hope this helps!!

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Well, I cleaned the IAC yesterday and it was still stalling, and if its job is to idle the engine up when the A/C is on then it is doing that.

Is it supposed to stall if the MAP sensor is disconnected? I knew it should have thrown a code, but I wasn't expecting it to stall out. I thought that the computer would have run in a loop if that had occured thus keeping the engine running.

What are the odds that I'm looking at a THIRD bad CPS? Could this part be failing due to heat? It checks out when I have tested it. I had a bad one for comparison so I know what I am looking for. Is there a way of testing it while the engine is running?

Your problem is not the CPS, if it were it would not run at all. The problem sounds like it is either the MAP or IAC. Swap each with a known good one. My guess is the IAC. I feel your frustration my friend as I went through an electrical problem not to long ago which turned out to be ground cable/connection.

Other posts have said that the CPS is heat sensitive. FSM says that the MAP, IAC, TPS, and ECT also have an effect on the ignition system. The FSM doesn't tell us how to check the CPS, but I've seen other post that have more info.

Your problem is so complicated, that I would try going back to Step 1. When the engine stops, do you know for a fact whether you are not getting spark or fuel? Spark, fuel, and compression (at the right moment of course) = combustion. You could try shooting spray start into the throttle body to see if that makes it fire. If it does, you have a fuel supply issue. If not, it must be spark.

Check PM.

Read this article...you have the same symptons...

http://motorage.search-autoparts.co...estandard//motorage/292005/169830/article.pdf

Good find McQue! And checking the FSM shows how to sync the CPS using his toothpick method. With motor at #1 compression TDC, toothpick has to go through hole in housing to align with hole in pulse ring. It looks like the sensor has to be removed to get to that hole.

Hi Chris. I feel your pain. I too have a 2000 jeep cherokee. I have been have very similar problems with my jeep for the past 6 months or so. Everyday on a cold start, it will start and run fine while i let it warm up. After 3 minutes or less it will mysteriously shut off completely as if it lost spark. However it starts right back up with no problems but also throwing no codes. Another strange thing it does is after a good warm up or long ride, after i shut it off and go to restart it while its still hot, it sputters and misses very bad, then slowly runs ok again. That was the only time it threw a code yielding the MAF sensor was bad, but i didn't replace it because most likely it detected that do to the very low idle and loss of vaccuum. I have been noticing poor gas mileage, loss of power, and even when its running ok it still has a little sputter. This problem seems to be getting worse and worse. Recently i noticed while driving it cut out twice. I found a service bulletin on the internet regarding similar symptons and it said to take it to the dealer to have the computer reprogrammed. I was at the dealer yesterday and they told me to run higher octane and injector cleaner for a week or two because of the gas these days and if it doesn't help to stop back and they will reprogram it. I don't think it has anything to do with fuel but i'll give it a try. I have a full tank of 93 and a bottle of lucas fuel injector cleaner and no change as of yet. My dad's 99 has 60000 more miles on it and feels like it has twice the power. I really want to get to the bottom of this and help anyone else who is having this problem. Did you take your's to the dealer to have the computer reprogrammed or try the higher octane?

I'm not sure i understand his toothpick method too well. I will have to read it again. I didn't try too many tests on my jeep yet due to my busy schedule. I noticed my throttle body is pretty dirty and i will clean it tomorrow although you tried that and mostly everything else with little or no results in fixing the problem. Please keep us posted.

Jeepin11,
Take a look at this article; http://motorage.search-autoparts.com...30/article.pdf It was sent to me by McQue on Post #6 of this thread. It seems that this may actually be the solution to the problem I have been having. I'm in the process of getting in touch with a friend of mine who is a mechanic and has a garage that I can use. In my case this is about the last thing I can try.

As far as dealerships and repair shops go, extreme caution is advised! The two most expensive parts I have bought and installed were on their recommendations. As far as I can tell, looking back, there was ZERO diagnosis done on their part. Don't get me wrong, there are great mechanics out there, but from my current experience, they are few and far between and I haven't found one yet.

My opinion on changing your gas is that this is just a red herring. I have owned my Jeep for 5-years run the rated octane for it and at every oil change (100% synthetic oil) I add a bottle of fuel injection cleaner to the tank. I have absolutely babyed this vehicle. It was the main drive for my wife driving to work and picking up the kids from school 5-days a week until this problem. This equals about 75-80 miles of daily driving, almost all highway. I have enjoyed almost 100k miles of trouble free driving and it is paid off to boot.

Running 93-octane may help it idle a little better and gain you a couple of MPG's, but I don't think it will solve your problem.

McQue said:

Read this article...you have the same symptons...

http://motorage.search-autoparts.co...estandard//motorage/292005/169830/article.pdf

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I will be preforming this procedeure later today. Wish me luck and thanks.

OK so what the procedure defines is that the timing for the coil packs is off due to the normal stretch of the timing chain. Is that correct? I will also be performing this procedure today so goodluck Chris and wish me luck also. Thanks.

Just for futher clarification if you haven't done this before, make sure to turn the engine to TDC only in the direction of normal rotation, to keep the cam chain tension the same way it is when it runs. Then you have to loosen the bolt at the drive base to rotate the housing until the toothpick drops in. Don't overtighten it back up and break it, there is no real force on this. It's just like timing a distributor on an old car.

winterbeater said:

Just for futher clarification if you haven't done this before, make sure to turn the engine to TDC only in the direction of normal rotation, to keep the cam chain tension the same way it is when it runs. Then you have to loosen the bolt at the drive base to rotate the housing until the toothpick drops in. Don't overtighten it back up and break it, there is no real force on this. It's just like timing a distributor on an old car.

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I will tell you that the toothpick doesn't feel exactly deadon but, I'm not exactly confident. The size of the tooth pick allows for quite a bit of play in both holes. Does anyone know exacly what size that hole is? I was trying to find a drill bit that would work, but I don't have anything close to that size.

Well, I have read throught the FSM, and it tells you to use the the toothpick for initial alignment...to get the sensor adjusted dead on the money, you need someone (dealer) with access to a DRB2 tool to perform the fine adjustment.
I personally would probably adjust it a very little in one direction to see if it gets better, worse, or fixes the problem. If all else fails you can always ask the dealer to check/adjust it for you.
My last thought is that you may have an intermittent heat sensitive wire connection between the cam position sensor and the pcm. Be aware that the crank position sensor is in the same circuit, and a wiring or sensor problem there can suck the signal down also. You might want to consider splicing a wire in parrallel from the pcm to the camshaft position sensor and/or cps to see if that helps.

If you read the article though, the auto shop teacher says that he has had better luck just with the toothpick than the DRB2 tool.

so chris. what happened with the cam sensor alignment.

So i was out cleaning all my ground connections today thinking that this should fix most electrical gremlins. It did not. still dies after the 30min window.

I started to dig into the distributor to try and realign the cam sensor. my 89 jeep does not have the tooth pick holes. in fact it looks like jeep flipped the insides upside down as compared to later models.

so how am i going to align the cam sensor without the ALIGNMENT HOLES.

Here is the brain teaser question.

If the cam sensor is misaligned due to timing chain stretch, which way due you turn the distributor housing to realign it, taking into account that the rotor and crank shaft rotate in a clockwise direction.

Gong to take a stab at this tomarrow.

morogpzxrr said:

So i was out cleaning all my ground connections today thinking that this should fix most electrical gremlins. It did not. still dies after the 30min window.

I started to dig into the distributor to try and realign the cam sensor. my 89 jeep does not have the tooth pick holes. in fact it looks like jeep flipped the insides upside down as compared to later models.

so how am i going to align the cam sensor without the ALIGNMENT HOLES.

Here is the brain teaser question.

If the cam sensor is misaligned due to timing chain stretch, which way due you turn the distributor housing to realign it, taking into account that the rotor and crank shaft rotate in a clockwise direction.

Gong to take a stab at this tomarrow.

Click to expand...

In answer to your last 2-posts It had no effect that I could tell, and I don't know which way to turn it. Mine was off just a little bit and I had to turn it clockwise just a hair to align it.
I'm setting this project aside, just for the moment:repair:. I have to find a job and I don't have a warm garage to work in . At the moment it is cold and windy and for the last two days we've had ice and rain. BURRRRRR! So, on warm weekends I'll get out and work on it and post my results, but I will have to avoid working on it during the week until I get the job situation worked out.

If anyone has any ideas on what's wrong with this Jeep feel free to post them. I will be checking back every once and awhile. Thanks

morogpzxrr said:

I started to dig into the distributor to try and realign the cam sensor. my 89 jeep does not have the tooth pick holes. in fact it looks like jeep flipped the insides upside down as compared to later models.

Click to expand...

Are you saying that your 2000 Xj has a distributor? i.e a true distributor with 6 ignition wires coming off it?